IP Range to CIDR Converter

Enter a start and end IPv4 address to find the minimal set of CIDR blocks that cover the entire range. This tool automatically calculates the largest possible supernets to minimize your firewall or configuration.

Define Range

Enter a starting and ending IP address above to calculate the covering prefixes.

Why use CIDR instead of ranges?

While many systems support ranges, most networking equipment (routers, firewalls, BGP) and cloud providers (AWS, Azure, GCP) use CIDR (Classless Inter-Domain Routing) notation. CIDR is more efficient for routing table lookups and is the industry standard for defining network boundaries.